Hydrocracking of a petroleum fraction with a silica-alumina-composite cracking catalyst



2,858,267 F A PETROLEUM FRACTION WITH R. M. KENNEDY ETAL HYDROCRACKING 0 A SILICA-ALUMINA-COMPOSITE CRACKING CATALYST Filed Sept. 2, 1953 Silica-Alumina Catalyst Oct. 28, 1958 HOURS ON sTREAM INVENTORS. ROBERT M. KENNEDY ALFRED E. HIRSCHLER CONARD K DONNELL ATTORNEY United States Patent 2,858,267 HYDROCRACKING or A PETROLEUM FRACTION WITH A SILICA-ALUMINA-COMPOSITE CRACK- ING CATALYST 3 Claims. (Cl. 208-111) This invention relates to the conversion of hydrocarbons. More particularly, the invention relates to a process of hydrocracking a specific hydrocarbon fraction boiling above the gasoline range to. produce a high yield of high octane gasoline.

The conversion of various petroleum hydrocarbon fractions by processes such as cracking, reforming, hydroforming, and the like, using a variety of catalysts and reaction conditions, has been described. Such heretofore described processes, however, are not suitable for converting the hydrocarbon fraction boiling substantially within the range of from about 375 to 500 F. to high octane gasoline in a single stage. Instead of achieving a good yield of high octane gasoline, there is produced gasoline hydrocarbons of relatively low octane rating usually in low yields, the production of normally gaseous hydrocarbons, such as propanes and butanes, is excessive,

and the reduction of catalyst activity is rapid. It has heretofore been necessary to employ at least two stages to convert a fraction boiling above the gasoline range to high octane gasoline. Such processes usually involve a cracking stage wherein a portion of the hydrocarbons are converted to hydrocarbons boiling in the gasoline range, and a reforming, or hydroforming, stage to upgrade the octane number of the gasoline. In the upgrading stage, the use of two catalysts in separate reactors with a hydrocarbon separation step between the reactors, or the use of two catalysts in a single reactor, has heretofore commonly been required.

An object of the present invention is to provide a single stage process for converting a petroleum hydrocarbon fraction boiling substantially within the range of from 375 to 500 F. to high octane gasoline in good yield. A further object is to provide a process for converting higher boiling hydrocarbons to high octane gasoline hydrocarbons wherein only minor quantities of normally gaseous hydrocarbons are formed, and wherein catalyst activity is maintained over long reaction periods. A still further object is to integrate the use of specific catalysts with a combination of reaction conditions to provide a process whereby higher boiling hydrocarbons are converted in a single stage to gasoline hydrocarbons of high octane number. Other objects will be apparent from the following specification.

It has now been found that a petroleum hydrocarbon fraction boiling substantially between 375 and 500 F.

can be converted in good yield to high octane gasoline by contacting the fraction with a specific catalyst under specific and correlated conditions of temperature, pressure, space velocity, and hydrogen to hydrocarbon ratio.

In accordance with the present invention, a petroleum hydrocarbon fraction boiling substantially within the range of from about 375 to 500 F. is contacted with a specific catalyst consisting essentially of silica, alumina, and molybdenum oxide or chromium oxide, as hereinafter defined, at a temperature of from 795 F. to 935 F., a pressure of from 500 to 1500 p. s. i. g. (pounds per square inch gauge), a space velocity of from 0.5 to 5 and a hydrogen to hydrocarbon mole ratio within the range of about 1:1 to 20:1. By operating within the stated limits with the specific catalysts of the invention, a conversion of the charge stock of at least 25 volume percent, based on the liquid charge, to gasoline having an octane number of at least 83 (research octane, clear) is achieved over periods of at least 70 hours of continuous operation. A change of the catalyst or of any variable outside of the stated range may give a low yield, say 10 volume percent, of high octane gasoline, or a relatively high yield of low octane gasoline, and in either event such operation is considered inoperative and outside of the scope of the present invention, which is directed to a process of obtaining high yields (above 25 volume percent) of high octane (above 83) gasoline over long periods of continuous operation (at least 70 hours).

The process of the present invention can conveniently be designated as hydrocracking. By hydrocracking, as used herein, is meant a process including the following reactions: (1) hydrocarbons boiling substantially within the range of from 375 to 500 F. are cleaved to form lower molecular weight hydrocarbons boiling within the gasoline range, which is usually from about F. to 350 F., but which can have an upper boiling point as high as about 430 F.; (2) naphthenes having a ring composed of 6 carbon atoms are dehydrogenated to form aromatic hydrocarbons; (3) paraffins are isomerized to branched or more highly branched paratfins, and naphthenes having a ring of 5 carbon atoms appear to be isomerized to naphthenes having a 6 carbon atom ring, which are then dehydrogenated to aromatics; (4) olefins, normally produced in the cracking processes, are hydrogenated to saturated hydrocarbons.

As above stated, a specific catalyst is employed in the present process. The catalyst consists of a synthetic silica-alumina cracking catalyst having deposited thereon from 2.9% to 11% molybdic oxide. Chromic oxide can be substituted for molybdic oxide as hereinafter explained. Synthetic silica-alumina compositions are well known as cracking catalysts, and heretofore described methods for their preparation may be employed in pre paring the silica-alumina portion of the present catalyst. For example, the silica-alumina portion of the catalyst may be prepared by impregnating silica with aluminum salts, by directly combining precipitated hydrated alumina and silica, or by joint precipitation of alumina and silica from aqueous solutions of their salts, and by washing, drying, and heating the resulting composition. In order for the resulting silica-alumina composition to give satisfactory results in the process of the present invention, it must have an activity index of at least 40, and preferably of from about 40 to 50, prior to depositing molybdic or chromic oxide thereon. Activity index, as used herein, is a measure of the eflicacy of a catalyst for cracking hydrocarbons and is determined by a method described by Alexander, Proceedings Am. Pet. Inst. 27 (III) 51 (November 1947). Molybdic oxide or chromic oxide is deposited onthis silica-alumina composition. The deposition may be in accordance with methods known to the art. For example, aqueous solutions of water soluble compounds of molybdenum or chromium, such as ammonium molybdate and chromium nitrate, may be employed to impregnate the silica-alumina composition. The resulting impregnated composition is then heated to convert the salt employed to the corresponding oxide, either molybdic oxide or chromic oxide.

As above stated, the concentrations of the catalytic components are important, and the concentration of each component must be Within a defined range. When employing molybdic oxide, the concentration thereof must be in the range of from 2.9 to 11% by weight of the final composition. When employing chromic oxide the concentration thereof must be between 6 and 20% by weight of the final composition. The critical nature of these limits are shown hereinafter by example. The

silica-alumina composition on which the molybdenum r chromium oxide is deposited must consist of from 50 to 90% by weight silica and from 50 to 10% by Weight alumina. The final catalytic composition thus contains, in percent by weight, from about 45 to 87.5% silica, from about 9 to 48.6% alumina, and from about 2.8 to 10% molybdic oxide. When using chiomic oxide the final composition contains, in percent by weight, from about 41.7 to 85% silica, from about 8.3 to 47.2% alumina, and from about 5.6 to 16.6% chromia.

Metals and metallic oxides, other than the oxides of molybdenum or Chromium, and carriers other than the synthetic silica alumina compositions described above, do not give satisfactory results in the process. For example, vanadium oxide on a silica-alumina composition as above described, molybdic oxide deposited on a synthetic silica-alumina composition having an activity index of 28, or on a clay mineral having a cracking index of 40, do not give satisfactory results.

The temperature to employ must be within the range of from 795 to 935 F. At temperatures above 935 F., a large amount of normally gaseous hydrocarbons are produced in the process, and the yield of gasoline hydrocarbons is low. At temperatures below 795 F, aromatic hydrocarbons are hydrogenated in the process. This is an undesired reaction which causes a reduction in the octane rating of the gasoline fraction. A temperature of substantially 887 F. is preferred, since this temperature converts the higher boiling fraction into high octane gasoline in good yield, only minor quantities of normally gaseous hydrocarbons being formed.

The pressure to employ in the present process must be maintained within the range of from 500 to 1500 p. s. i. g. At pressures below 500 p. s. i. 'g., the activity of the catalyst rapidly decreases because of excessive coke formation thereon. At pressures above 1500 p. s. i. g., aromatics are hydrogenated to naphthenes. If higher temperatures are employed to overcome this undesired hydrocarbons. The process is not operable with other fractions, such as for reforming a gasoline fraction, as shown hereinafter by example, or for converting a fraction boiling above 500 F. The fraction to employ preferably boils over a range of at least 60 F. with an initial boiling point of at least 375 F. and an end point not above 500 F. The fraction should have at least 10% by volume naphthenes, and preferably has from 12 to 60% by volume n'aphthenes. Olefins may be present and do not appear to deleteriously affect the process, but in the preferred straight run petroleum the concentration thereof is usually less than about 3% by volume.

The presence of hydrogen is absolutely essential to the process. The mole ratio of hydrogen to hydrocarbons charged, however, can be substantially varied and good results obtained therewith. Within the limitations of the several variables of operation, as above described, the hydrogen to hydrocarbon mole ratio can be varied from 1 to 20 with good results. The preferred conditions of operation are such that the hydrogen partial pressure is within the range of from about 800 to 1400 p. s. i. g.

The following examples illustrate the process of the invention and demonstrate the critical nature of the limitations as set forth above. In the tables, under Yield of Products, the dry gas yield is given in weight percent of the charge stock and butane and gasoline yields are given in volume percent of the liquid charge, unless otherwise stated. As used in the examples and tables, "gasoline" is the debutanized fraction boiling up to 350 F., i. e. is the fraction containing pentanes and boiling up to 350 F. Research octane, clear, is determined by ASTM Test D 908, and research octane+1.5 cc. TEL tetra ethyl lead) is determined by the same test with the stated quantity of TEL added to the gasoline. The most frequently used and preferred catalyst of the examples consists essentially of a silica-alumina cracking catalyst having deposited thereon 5% M00 The silicaalumina cracking catalyst prior to deposition of M00 contains 11% alumina and 89% silica, has a cracking genation obtained at high pressures, at large conversion index of 46 and was prepared by coprecipitation, wash to normally gaseous hydrocarbons, instead of to gasoing, and drying. The molybdic oxide was deposited on line hydrocarbons, is observed. In general, relatively high his Cracking catalyst by impregnating the silica-alumina pressures f from about 1000 to 1300 p. s. i. g. are precomposition with an aqueous solution of ammonium ferred, since as shown hereinafter by example, the gasomo y i drying and heating the resulting composition line yield is enhanced thereby. to a temperature of about 1100 F. In the following The space velocity must be maintain d withi range examples and tables this final catalyst is identified as from 0.5 to 5. It is preferred to employ a space velocity catalyst A." of substantially 1 to 2, since there is obtained a high MP 1 838011116 Yield of hlgh Octane number, aIld y low COII- To illustrate a preferred embodiment of the process of Vefslon of hydrocafbqll's t0 Q Y gaseous y r- 50 the invention, catalyst A was used to hydrocrack a bons- At Space Velocltles below hlgh Ylld Of 1101 straight run petroleum fraction boiling between 400 and Influx 821860118 hYdf0Cafb0n 1$ Obtalned, and at Space 500 F. The charge fraction was composed, in volume 310011168 0f B Y thfi fi of gasoline is adversely percent, of 18% aromatics, 28% paraflins, 40% monoy Sp velocltyr f used- 0 1S 1 11 5r cyclic naphthenes, 13% dicyclic naphthenes, and a small the hqllld hourly Space veloclty, Whlch 18 the llqllld amount of other materials. The petroleum fraction, at a volume of hydrocarbons charged per volume of catalyst space velocity of 1, admixed with hydrogen Was con- P U tacted with a catalyst maintained at a temperature of The process of the invention converts petroleum hydro- 887 F., and at a pressure of 1000 p. s. i. g. The hydrocarbon fractions boiling in the range of from 375 to gen to hydrocarbon mole ratio, and results obtained, are 500 F. in good yield to high octane gasoline hydroshown in Table I.

Table I Hours on stream 0-24 24-48 48-70 -94 94-118 118- 142- 154- 178- 202- 226- 250- 258 282- 142 154 178 202 226 250 258 282 306 Fig/hydrocarbon (Mole ratio). 11.9 11.9 12.6 16.0 16.9 17.1 17.0 16.0 15.4 16.1 16.7 16.0 15.8 16.0 Yield of Products:

Dry gas yield, wt. per- .cent 12.7 8.7 6.6 11.9. 8.8 7.4 6.5 6.3 5.3 4.6 5.2 3.7 4.7 4.4 Butane yield, vol. percent 28.1 19.5 15.0 27.6 20.7 15.9 14.7 10.6 10.9 10.5 8.6 7.1 8.6 8.0 Gasoline yield, vol. percent 50.0 41.0 36.9 48.9 39.5 35.6 34.5 34.8 28.0 26.3 25.5 25.6 23.9 23.1 Research octane, clear 85.1 86.0 85.8 86.6 86.9 86.7 86.1 86.9 86.8 86.7 86.7 86.7 86.9 86.5 Research octane with 1.5 cc.

TEL 94.0 94.3 94.8 94.7 94.5 94.7 94.3 95.2 94.9 94.3 95.0 94.8 94.6 94.4

1 Catalyst regenerated, by burning 0ft carbon, after 70 hours operation.

Asshown by the table,"the process of the present ini vention gives a high yield of high octane gasoline for many hours. Catalyst regeneration, as shown in the table, after 70 hours of operation, does not adversely affect the process. Thus, the gasoline yield was above 25 volume percent 188 hours after regenerating the cataperature of 887 F., a pressure of 1000 p. s. i. g. and a space velocity of 1. The hydrogen to hydrocarbon ratios Table II Catalyst B Catalyst C Catalyst D Hours on stream 6-31 31-55 55-79 -24 24-48 48-69 69-97 0-24 24-48 48-62 62-88 92-111 Iii/hydrocarbon (Mole ratio) 8. 6 7.0 5. 9 10.7 11. 3 12. 2 11.9 7. 91 8. 38 6. 47 8. 44 6.1 Dry Gas Yield (Wt. Percent) (01 to Ca hydrocarbons) 19. 6. 7 5. 6 12. 8 8. 7 8. 5 8. 4 9. 7 7. 2 5. 3 4. 4 BUtBHBS (Volume Percent) 27.0 11. 7 8. 7 30. l 19. 0 10. 1 15. 2 18. 9 16. 9 10. 1 11. 2 Gasoline yield (debutanized, 350 F. end

point) V01. percent 48. 3 32. 3 25.7 50. l 39. 7 36. 7 35. 2 36. 7 32. 8 25. 5 25.0 Gasoline fraction-Engler Dist, F.:

I. B. P 102 102 100 102 97 97 109 102 107 108 96 97 0%. 132 134 132 133 129 127 141 130 134 133 130 129 50%.- 197 209 209 201 199 195 211 199 202 205 206 207 90% 290 303 303 299 298 296 301 302 304 302 302 300 E. P. 318 323 324 323 320 321 326 322 324 324 321 325 Recovery. 99. 0 98. 5 98. 5 97 97. 5 97. 5 97. 5 98. 5 98. 5 99. 0 98. 0 98. 0 F-l clear 86. 5 84. 7 84. 9 86. 7 85. 6 84.9 85. 3 87 86. 5 86. 3 87. 2 F1+1.5 TEL 94. 5 93.1 93. 2 94. 7 g 93. 9 93. 8 t 93. 6 95. 4 95. 2 94. 3 94. 1 94. 3 Volume percent aromatics 26.8 23. 4 20. 6 27. 9 25. 2 22.8 25.1 26. 8 16. 8 24. 4 25.4 24. 6 Volume percent olefins 3. 2 6. 5 10. 9 2.3 3. 6 4. 8 6.1 5.0 6. 4 1 7. 4 8.0 9. 2 Volume percent parefiins 52. 8 54. 7 54. 5 48. 5 Volume percent naphthenes 17. 0 16. 5 17. 9 20. 3

lyst. The high octane number and good lead susceptibility of the gasoline fraction show the excellent results achieved in accordance with the process of the present invention. The relatively low yields of dry gas and butanes are also to be noted. These products are valuable, however, so that their formation in minor quantitles is not disadvantageous. The dry gas can be used as a fuel and the butanes, consisting of a mixture of normal and isobutane, can be used in processes such as alkylation to form valuable hydrocarbons, or the butanes may be included in the gasoline fraction especially when i the gasoline is to beused in cold weather engine operation.

EXAMPLE 2 Three catalysts were prepared by depositing various quantities of molybdic oxide on a silica-alumina cracking catalyst having about 11% Al O and 89% S102. Prior to the deposition of molybdic oxide, the cracking catalyst had a cracking index of 46. The quantities of molybdic oxide deposited on the silica-alumina catalysts 1 were 2.9% (catalyst B), 4.4% (catalyst C) and 10.2% (catalyst D). The catalysts were employed, under comparable conditions, for hydrocracking a straight run petroleum fraction. The straight run charge stock had the following boiling characteristics: an initial boiling point of 410 F., distilled at 418 F., 50% distilled at 449 F., 90% distilled at 472 F., and an end point of 490 F. The average molecular weight of this charge stock was 185, and it was composed of 16 volume percent aromatics, volume percent paraflins, 41 volume percent monocyclic naphthenes, 12 volume percent dicyclic naphthenes, and 1 volume percent of other materials.

All of the runs of this example were made at a tem- As shown by the data and figure, catalyst B gives a good yieldof gasoline for a short time, but rapidly loses its initially high activity. Catalyst D gave a relativcly low yield of gasoline throughoutthe run. containing 4.4% M00 gave good results and maintained high activity for many hours. Thus, after hours of operation, catalyst C was' giving a steady yield of about 35% gasoline, while catalysts B and D were giving a yield of about 25%. For comparison, the data obtained with the silica-alumina catalystwithout M00 deposited thereon is included in the figure. If a gasoline fraction of a wider boiling range is desired, say a fraction having an end point of 400 F., the yield obtained in the process is increased accordingly. When amounts of molybdic oxide below 2.9%, or above 11%, are employed, the yield of gasoline rapidly decreases to below 25% so that the process is rendered inoperative thereby. Hence the ,quantity of molybdic oxide deposited on the silica-alumina composition must be from 2.9 to 11% by weight of the silica-alumina composition.

EXAMPLE 3 In order to demonstrate the use of chromic oxide in place of molybdic oxide, two catalysts were prepared. One catalyst contained 11% chromic oxide. 28% alumina, and 61% silica (catalyst E), the other containing 9.1% chromic oxide, 10% alumina, and 80.9% silica (catalyst F). The activities of both of the silica-alumina compositions employed, prior to the depositions of chromic oxide thereon, were above 45. The procedure and charge stock of Example 1 were employed using a temperature of 887 F., a pressure of 1000 p. s. .i. g., and a space velocity of l. The hydrogen to hydrocarbon mole ratios and results obtained are shown in the following Table III.

Table III Catalyst E Catalyst F Hours on stream 0-30 30-54 54-78 0-24 24-48 48-72 72-78 HQ/ YdI'OOBIbOD. (Mole ratio). 13.3 14.0 13.3 9. 5 7. 7 7. 4 8. 8 Yield of Products:

Dry gas, wt. percent..." 9. 4 5. 0 5. 6 9. 8 5. 9 5. 2 3. 8

Butanes, Vol. percent. 15.8 9. 6 7. 8 21. 1 10.9 11.0 6. 4

Gasoline, Vol. percent 41.0 28. 7 25.7 46. 4 33.7 28. 9 26.6 Research octane, clear. 84.0 83. 7 83. 2 85.3 84. 3 84.2 L Research octane +1.5 cc.

TEL 93. 4 92. 3 91. 9 94. 0 92. 8 '92. 9

Catalyst C,

Asashown by. Table iIlLlboth catalyst E and.catalyst .F gave .a high octanegasoline in good. yield after more than 70-hours operation;

EXAMPLE In orderto demonstratethetailureofcatalysts other than'those"herein'claimed' to'givecomparable results in the present process, various catalytic compositions heretively low cracking-index, Catalyst L consisted of 5.1%

of -M 3deposited.-,on;;acid-; activated montmorillonite. 1- Prior: toi deposition; of. vmolybdic oxide, the montmorillonitethadmntactivity index .of 40. Catalyst M consisted essentially of chromieoxidedeposited on the same:-

silica-magnesiat composition; as 1 catalyst I, which -was .1-11 commercially available silica-magnesia cracking catalyst.

"In each instance thecharge stock was the same as employed in Example2 and the same conditions of operation were employed except as otherwise indicated in Table V. The .data obtained: are as shown by Table V.

Table V Catalyst K Catalyst L CatalystM Hours on stream 0-24 2442 0-22 2246; 4670 70-94. 94-118 118-131 024--- 24-48 4872 72-96 Hzlhydrocarbon(Mole ratio) j12.5. v 12.0 11.9 13.3 14.2 13.3 Yield of Products:

Dry gas,.wt. Percent 2.8 4.0 4.5 4.0 3.7 4.2

Butanes, Vol. Percent..- 4.7. 6.2. 6.9 6.5 4.1 1.8

Gasoline, Vol. PercenL. 17. 5 18. 9. 34. 9 1 38. 7 32. 2 29. 8 Research octane, clear... 83. 5 84.0 73. 6 72. 8 72.8 73. 7 Research octane 1.5 cc. TEL 92. 2 92. 7 85.0 1 85.2 84. 6 85.9

inum:thereon,=of about.30.. Catalyst J consisted of 0.5%

platinum depositedmn a commercially-available silica magnesia :cracking catalyst. The hydrogen to- :hydrocari bonzmole ratio and results obtained therewith are shown in thefollowingTable IV.1- Each catalyst wasrun with v the: same hydrocarbon=charge stock as Example-2 under the same conditions therein describedtexcept; as otherwise indicated in .thetable.

As will be noted from the-data very poor results were.

obtained with each. of'these catalyst. Thus, using vanadium oxide, a poor yield of gasoline-was obtained andthequality of the gasoline rapidly decreased. Using boria onaluminathe yield of gasoline was insignificant. Using platinurnon a silica-alumina.cracking.catalyst:having an activity index of 30 gave-a low octane. gasoline-product as did the other platinum catalyst.

As .shownwby tth-e: table, silicaralumina compositions; havinga cracking activity. -of -less than 40. do not give.

good results,.,and';natural.minerals, used in place of .syn-.

thetic.;silica-a1umina. compositions, .do not give good. ref. sults. Thus,;.catalys tzK gavefla poor..yield of. gasoline I I and-catalystsL and -M ave lowoctane gasoline.

EXAMPLE '6 In. order .to. illustrate .the importance of maintaining the.

quantity ofnaluminauinthe syntheticsilica-alumina composition within the -range..of from. 10% .to thereof, the following catalysts were prepared. Catalyst N con--.

sisted essentially of 5.4%..MoO on a synthetic silicaalumina cracking catalyst containing 32% alumina and 68% silicay-the cracking catalyst prior. to depositionof molybdic oxide haduan: activity index of about 50. Cata-.

lyst' O consistedof l9'%--chr'omic:oxide, 25.5% silica and 55.5% alumina, .which,.forzcomparison,is the equivalent.

of havingrabout 23.5 %.chromia.deposited on a composition consisting of 31.5% silicaand 68.5% alumina. It

Table IV Catalyst G Catalyst H 1 Catalyst I Catalyst 3' Hours on stream 0-24 24-48 26-50 50-67 024 24-48 48-72 024 24 48 Hz/hYdIOCfil'bOD (Mole ratio).... 7. 2 5. 9 4. 4 5. 1 6.1 6. 0 10.5 6. 9 6. 4 Yield of Products: 1 1

Dry gas, Wt. percent 5. 6y I 2. 0 2.1 2.3. 1.6

Butanes, Vol. perce t. 9.0 3.6 4. 5 4.1 2.7

Gasoline, V01. perccn 25. 5. 15. 9 8. 9 33. 9 24. 9 Research octane, clear. 1 85. 8 82. 7 1 69. 4 67.8 Research octane +1.5 cc. TEL; 94.1 91.8 81. 6 80.9

1 A space velocity of 4, instead of 1, was used.

EXAMPLE 5 In orderto demonstrate the importance of employing a synthetic silica-alumina cracking catalyst having an activity index .of above 40, and of maintaining the silicaalumina ratio within the stated value, various catalysts were prepared as follows: Catalyst K was prepared by depositing 5% M00 on a synthetic silica-alumina cracking catalyst having a .cracking'index'of about 30; this catalyst was identical tocatalyst-"A except--for-the rela- Catalyst P straight run petroleum fraction boiling between 375 and 460 F., having 12.9 vol. percent aromatic Y Catalyst 0 1 Table VI Dry gas, Wt PercenL- Butanes, Vol Percent ctane, clear ane 1 5 cc. '1'

1 Temperature of 932 F. used instead of 887 F.

It will be noted that catalyst N gave good results, the proportions of catalyst constituents bein fined ranges.

Hours on stream Ila/hydrocarbon (Mole ratio) Yield of Products:

Research 0 Research oct g within the des, 1.1 vol. Catalysts O. and P were inoperative in the percent olefins, 0.031 wt. percent sulfur, and the remainder process, the proportions of catalyst constituents being outbeing naphthenes and parafiins, was employed in the side the defined ranges. process following the procedure of Example 1., The hy- EXAMPLE 7 drogen to hydrocarbon mole ratio was maintained within In order to show the importance of maintaining the ined are CatalystA T able VIII 5 Amoo 1% 08 the range of from 13.7 to 14.2. Results obta shown in the following Table VIII.

Dry gas, Wt. Percent-..

Hours on stream........

Yield of Products:

utanes, Vol. Percent.

Research octane, clear Research 0 ctane 1.5 cc. TEL Gasoline fraetlon:

Aromatics, Vol. Percent Sulfur, Wt. Percent- EXAMPLE 9 In order to illustrate the eifect of temperature in the esent process, the procedure of Example 1 was repeated at temperatures of 932 F. and 752 F., using catalyst A. The data obtained are shown in the following Table VIII. a good yield of high octane gasoline was R O 2 3 9 T. t P A 5 4 g. c 333 uW yS d m n mim ar .R i hF .w? R

charge stock boiling range within the limits herein described, the procedure of Example 1 was re catalyst A. The charge stock was a stra leum fraction boiling between 250 and 500 tion contained 53.1 volume percent gasolin carbons boiling between 250 and 350 Catalyst A mwm Catalyst A Table VII Hz/hydrocarbou (Mole ratio). Yield of Products:

tained are shown in the following Table VII.

Hours on Stream Dry gas, wt. percent..-

Butanes, vol. percent Gasoline, vol. percent.- Research y large At 752 R, which is quired in the process,

e octane number of the gasoline products was so low within product after allowance ge introdry gas emental The formation of and butanes was actually greater than the incr increase in gasoline.

octane, clear ane 1.5 cc.

It will be noted that the octane number of the was very low as was the gasoline yield EXAMPLE 8 To-show a preferred embodiment of the invention, a the limits of from 795 to 935 F.

Research oct 1 500 p. s. i. g. instead of 1,000 p. s. i. g.

for the hydrocarbon'boiling in the gasoline ran duced by the charge stock.

Table IX Catalyst A Catalyst A Temp. F.) 932 752-,

Hours on stream -24 24-.48 48-72 72-100 4,8172 1091-132 Hz/llYdIOOflI'bOll (Mole ratio) 10.7 111.6 l 9.3 E $11.1 1 a? 12.7 11.8. Yield of Products (Wt; percent'ioi 1 1 charge):

Dry gas i 17.4 i 12.0 9.7 8.9 4.7 I 2.9

Butanes. 18.1 1 11.5 10.6 1 7.5 9.6 8.7

Gasoline. 36.8 29.0 26.2 22:9 40.8 36.0

Recycle 26. 9 47. 8 51. 9 58. 9 46.0 50. 2

Gasoline d, percent- 42 33. 5 30. 0 25. 4 48. 1 42. 0 Research octane, clear 86.2 85. 8 85. 8 85.4 80.0 81.3 Research ostane+1.5 cc. TEL 94. 2 94.8 94.4 94. 0 90. 2 90.9

EXAMPLE 10 As shown by the tabl'e,.a good yield {of high octane.-

In.or.der-. to illustrate. theimportance of pressure and space velocity, the procedure'of Example 1 was:repeated using 1200 pas. i. g. and space velocityv of .1 and 2 respectively. .The data obtained are shown in the following Table X.

gasolinewas obtained with this charge stock," showing. that the charge stock can be recycled to substantial .ex?

tinction.

The invention claimed .zisi 1. Process of hydrocracking. a petroleum. hydrocarbon Table X Catalyst A 1 Catalyst A 2 Hours on Stream 0-24 24-48 1 48-72 72-96 96-109 0-24 24-48 48-72 72-96 96-108 108-132 132-156 Iii/hydrocarbon (Mole ratio) 14. 6'. 14.6 14. 9 14. 9' I 15.1 12. 5 12.6 13.0 13.4 14.2 12.4 12.6 Yield of Produsts (Wt. percent of charge):

Dry gas 16.0. 14.1 11.9 11.2, i 12.1 9.9 6.7 4. 7 3.4 4.1 5.4 3.9

Butanes. 25.0 21.2 19.3 17.3 16.5 17.7 11.1 9.0 7.1 6.1 6.7 6. 2

Gasoline 1 50.4 47.6 45.3 a 43.7 I 1 43.6 40.5 30. 5 28.6 25. 6 24.4 25.6 24. 6

Recycle. i 8.7 17.6 22.8 29.4, 29.5 31.5 45.4 57.9 62.5 64.6 62.3 66.7

Gaso1ine-Yield,,Vol. percent" 61.1 56.9 55.4. r 50. 7.. 51. 5 -47. 8 35.0 32.4 29. 2 28.1 29.4 28.3 Research octane, clear 84.3 85.4 85.0 84.4 t 84.6 1 88.0 85.8 86.2 86.0 85.9 86.1 85.9 Research octane+1.5- cc.- TEL 93.4 94.0 93.5 93.3 93.5- s 96.0 94.3 94.1 94.4 94.2 94.2 94.4

At pressures above 1500 p. s. i. g.,'the-- octane number is too low probably because of the hydro- 1 genationof naphthenes and at space velocities of above 5, the process is inoperative in that the yield of gasoline is very low.

EXAMPLE 11 In order to demonstrate the use of unconverted or insufficiently converted hydrocarbons in the process as recycle charge stock, hydrocarbons boiling from. about 400 to 500 F. separated from the gasoline product of previous runs, performed in accordance with the process of the present invention, were used as charge stock together with catalyst A and the same conditions employed in Example 1. The results obtained are shown in the v following Table XI.

Table XI Catalyst A Hours on stream 0-24 24-48 48-72 72-96 96-107 lib/hydrocarbon (Mole ratio) 12. 4 12. 4 12. 2 12.8 12. 6 Yield of Products (Wt; Porccut ;of charge):

Dry Gas 13.3 7.5 5.2. 4.8 3.

Butanos 19.0 11.0 9.2 a 7. 6 1 6.

Gasoline 44. 5 33. 3 28.3 25. 1 22.

Recycle- 21. 0 44. 1 56. 0 61. 1 64. GasolineYi'eld Vol.1ercent 53.0 39.1, 3351 28.8 25. Research octane, clear. 86.1 86.5 85.4 85.5 86. Research octane+1-.5 cc. TEL. 94.5 94. 8 i 94.0 94.4

fraction boiling within the range of from 375 F. to 500 F. and containing at least 10% by volume naphthenes,

which comprises contactingan admixture of'said .fraction and-hydrogen with a catalystconsisting essentially of a synthetic silica-alumina cracking catalyst having a cracking-index of at least 40, a silica content of from.w50 to I 90%, and an alumina content'ofi from 50 to:10%'; said silica-alumina crackingcatalyst'having deposited thereon:

a material selected from'the group consisting-of'molybdic oxide in an amount of from 2.9% to 11% of said silicaalumina catalyst and chromic oxide in an amount of from 6% to 20% of said silica-alumina catalyst, said contacting being at a temperature of from 795 F. to- 935 F., a pressure of from 500 to 1500 p. s. i. g., a space velocityof from-0.5 to 5, and a hydrogen to hydrocarbon mole ratio of from 1:1 to 20:1, and separating fromothe'z. reactionproducts a gasoline-fraction having an octanenumber of. at least '83. Y

2. Process of .hydrocrackinga petroleum hydrocarbon fraction boiling within the rangerof from 375.". F. to 500 F. and containingfrom 10%"v to 60% by volume naphthenes which comprises contactingan admixtureof said mole-ratio of from-1z1 to 20:1, continuing saidcontacting for a continuous period of at least hours, and separating from the reaction products a gasoline fraction in a yieldof'atleastz25.volumepercent; based on the liquid 13 products of the reaction, said gasoline fraction having an octane number of at least 83.

3. Process of hydrocracking a petroleum hydrocarbon fraction boiling Within the range of from 375 F. to 500 F. and containing at least about 40% by volume naphthenes, which comprises contacting an admixture of said fraction and hydrogen with a catalyst consisting essentially of a synthetic silica-alumina cracking catalyst having a cracking index of at least 40, a silica content of from 50 to 90%, and an alumina content of from 50 to 10%, said silica-alumina cracking catalyst having deposited thereon a material selected from the group consisting of molybdic oxide in an amount of from 2.9% to 11% of said silica-alumina catalyst and chromic oxide in an amount of from 6% to 20% of said silica- 5 2,709,151

14 alumina catalyst, said contacting being at a temperature of from 795 F. to 935 F., a pressure of from 500 to 1500 p. s. i. g., a space velocity of from 0.5 to 5, and a hydrogen to hydrocarbon mole ratio of from 1:1 to 20: 1, and separating from the reaction products a gasoline fraction having an octane number of at least 83.

References Cited in the file of this patent UNITED STATES PATENTS 2,585,337 McKinley Feb. 12, 1952 2,676,907 Oblad et a1 Apr. 27, 1954 2,703,308 Oblad et a1. Mar. 1, 1955 2,708,180 Von Feuner et a1. May 10, 1955 Nonenrnacher et a1 May 24, 1955 

1. PROCESS OF HYDROCRACKING A PETROLEUM HYDROCARBON FRACTION BOILING WITHIN THE RANGE OF FROM 375*F. TO 500* F. AND CONTAINING AT LEAST 10% BY VOLUME NAPHTHENES, WHICH COMPRISES CONTACTING AN ADMIXTURE OF SAID FRACTION AND HYDROGEN WITH A CATALYST CONSISTING ESSENTIALLY OF A SYNTHETIC SILICA-ALUMINA CRACKING CATALYST HAVING A CRACKING INDEX OF AT LEAST 40, A SILICA CONTENT OF FROM 50 TO 90%, AND AN ALUMINA CONTENT OF FROM 50 TO 10%, SAID SILICA-ALUMINA CRACKING CATALYST HAVING DEPOSITED THEREON A MATERIAL SELECTED FROM THE GROUP CONSISTING OF MOLYBDIC OXIDE IN AN AMOUNT OF FROM 2.9% TO 11% OF SAID SILICAALUMINA CATALYST AND CHROMIC OXIDE IN AN AMOUNT OF FROM 6% TO 20% OF SAID SILICA-ALUMINA CATALYST, SAID CONTACTING BEING AT A TEMPERATURE OF FROM 795*F. TO 935* F., A PRESSURE OF FROM 500 TO 1500 P. S. I. G., A SPACE VELOCITY OF FROM 0.5 TO 5, AND A HYDROGEN TO HYDROCARBON MOLE RATIO OF FROM 1:1 TO 20:1, AND SEPARATING FROM THE REACTION PRODUCTS A GASOLINE FRACTION HAVING AN OCTANE NUMBER OF AT LEAST
 83. 